The invention relates to a projector such a projector may have a collecting reflector as a working surface and a casing arranged above this reflector and carried by a lateral stand, in which casing a deflecting mirror, a projection lens and a lamp housing are arranged, whereby the lamp housing has a concave mirror, a condenser lens and a lamp which is in a set position and is arranged between the latter.
With this type of projector, the light radiated by the lamp and focused by the condenser lens is thrown on to the reflector. The latter is usually constructed as a Fresnel lens and mirror-coated so that the light can be reflected in a direction on to the projection lens and on to the deflecting mirror. If a sheet is placed on to the working surface and if the sheet is written on, then the image of the writing can be projected on to a surface with the air of the deflecting mirror so that it can be easily seen by a large number of spectators.
With known projectors of this type it is very difficult to replace the lamp. Essentially this has two causes, one of which consists in the fact that the lamp is fairly inaccessible because of the design of the lamp housing and parts of the lamp housing have to be removed in a relatively complicated manner in order to be able to take out the lamp from its socket. The second cause is connected with the previously insufficient cooling resulting from the previously relatively compact design of the lamp housing which impairs the radiation of heat. This results in the fact that, in the case of a defect in the lamp, a certain period of time has to elapse before the parts of the lamp housing which are to be dismantled in order to change the lamp can be handled. This is very disruptive if the defect in the lamp arises during use. In addition, a tool is required for the purpose of dismantling the relevant parts of the lamp housing and this is also disadvantageous.